This invention concerns multi-speed drive and more particularly a two-speed clutch drive in which drive is transmitted from an input member to an output member so as to drive the output member at either a high or low speed and in which a neutral condition of the clutch is also enabled with drive between the input member and output member interrupted. Such multi-speed drives are utilized in a variety of applications such as in clothes washing machines where an electric drive motor is utilized to drive the washing machine components. Commonly, a single drive motor is employed to cause oscillation of the washing machine agitator at relatively low rotative speeds, and during the spin cycle the same drive motor drives the basket at relatively high speed.
In addition, many washing machines employ differing agitator speeds for gentle or regular wash cycles to suit the washing action to various fabric types.
For such washing machine applications, a particularly advantageous drive arrangement is the use of a two-speed clutch in which the output rotation of the drive motor shaft is transmitted to the machine components with a two-speed clutch having a first mode in which the rotation of the input motor shaft is transmitted to an output member at the same rotative speed and in a second mode a controlled slip of the clutch produces a reduced speed of the output member relative to the rate of rotation of the drive motor.
This arrangement is described in U.S. Pat. No. 2,869,699, assigned to the assignee of the present application.
The two-speed drive depicted in this patent includes an inner drum constituting a rotary input member surrounding the motor shaft and concentric outer drum constituting a rotary output member which is adapted to drive the washing machine transmission input. In these applications, the motor is adapted to drive the washing machine drain pump by means of a shaft extension fitted with a coupling to the input shaft of the pump or pumps.
The arrangement described in that patent includes centrifugally actuated primary clutch shoes driven by the motor or input shaft which centrifugally expands the shoes upon rotation thereof to move into driving connection with an inner drum. The drive between the outer drum and the inner drum is controlled by two separate clutch set arrangements. The first clutch set includes clutch shoes which are spring biased into engagement with the inner drum and which are positively connected and driven by the outer drum, with centrifugal force acting on the shoes of the clutch tending to reduce the engagement force and create slippage, resulting in a low speed drive between the inner drum and the outer output drum and correspondingly between the input shaft and the output drum.
The second clutch set establishes a drive and is provided by a direct drive clutch carried on a carrier plate which is rotatably mounted on the motor input shaft. Upon rotation of the carrier plate by frictional drive of the carrier bearing assembly arrangement, the clutch shoes are urged by centrifugal force into driving engagement with both the inner and outer drums thereby establishing direct drive.
Control between high and low speeds is achieved by a solenoid actuator restraining or freeing the carrier plate for rotation, thus either allowing the direct drive to be activated or preventing its activation by prevention of rotation of the carrier plate.
U.S. Pat. No. 2,869,344 shows another variation of this approach in which centrifugal clutching action is staged in operation to provide a two-speed friction drive.
Copending application Ser. No. 072,273, filed Sept. 4, 1979 discloses an improvement for this clutch design in which the intermediate direct drive clutch components are carried by the inner and outer drums respectively to eliminate the need for the carrier plate and to produce other improvements as described in detail in that application.
This elimination of the carrier plate significantly reduces the cost of the unit.
In these clutching arrangements, there is not provided a neutral condition of the clutch which can be a disadvantage in some washing machine configurations.
As noted, the same motor is often utilized to drive a pump which empties the basket or tub water from a washing machine after each wash and rinse cycle. It is often advantageous for a pump down of the basket to be carried out prior to establishing drive to the basket in order to improve various wash performance characteristics, water entrainment, sudsing, etc.
Since the same motor drives the drain pump, this requires either a delay in the initiation of the clutching action due to mechanical or electronic delay means, or advantageously this could be achieved by the provision of a neutral mode of the clutch, in which the drive shaft is rotated but no drive transmitted to the output drum.
It is of course of great advantage in such applications that any controls for such clutching arrangement be simple and reliable, i.e., to be composed of a minimum number of parts and to involve only simple movements of the control mechanism.
Accordingly, it is an object of the present invention to provide a two-speed drive clutch of the general type described in which there is provided a neutral condition of the clutch in which the input shaft rotation is not transmitted to the output rotary drum in one mode of operation of the clutch unit.
It is another object of the present invention to provide such two-speed clutch with neutral having the control arrangement of extreme simplicity and reliability requiring a minimum number of additional parts, such feature being incorporated in two-speed clutch unit at minimal cost and will operate with excellent operating characteristics.
It is yet another object of the present invention to provide such two-speed clutch which does not require an intermediate carrier plate, but is readily controllable to either establish slow or direct drive from the inner drum to the outer drum.